Method of coating a porous substrate with a thermoplastic material from the outside of the substrate

ABSTRACT

A method of coating a first porous substrate with a thermoplastic material comprises the steps of: rotating the substrate about an axis of the substrate; and applying the material in a liquefied state onto the substrate, wherein the step of applying is performed from the outside of the substrate. According to another embodiment, a method of coating a porous substrate with a thermoplastic material comprises the steps of: connecting a first porous substrate to a rotator; rotating the substrate about an axis of the substrate; pumping the material in a liquefied state from a receptacle to an application head; and applying the material in a liquefied state onto the substrate, wherein the step of applying is performed from the outside of the substrate. In certain embodiments, the material coated on the substrate is used to help remove at least a portion of a filtercake.

TECHNICAL FIELD

A method of coating a first porous substrate with a thermoplasticmaterial comprises the steps of: rotating the substrate about an axis ofthe substrate; and applying the material in a liquefied state onto thesubstrate, wherein the step of applying is performed from the outside ofthe substrate. In some embodiments, the method includes coating a secondporous substrate with the thermoplastic material. The method of coatingcan include coating the substrate with a desired quantity of materialper a given length of the substrate.

SUMMARY

According to an embodiment, a method of coating a first porous substratewith a thermoplastic material comprises the steps of: rotating thesubstrate about an axis of the substrate; and applying the material in aliquefied state onto the substrate, wherein the step of applying isperformed from the outside of the substrate.

According to another embodiment, a method of coating a porous substratewith a thermoplastic material comprises the steps of: connecting a firstporous substrate to a rotator; rotating the substrate about an axis ofthe substrate; pumping the material in a liquefied state from areceptacle to an application head; and applying the material in aliquefied state onto the substrate, wherein the step of applying isperformed from the outside of the substrate.

BRIEF DESCRIPTION OF THE FIGURES

The features and advantages of certain embodiments will be more readilyappreciated when considered in conjunction with the accompanyingfigures. The figures are not to be construed as limiting any of thepreferred embodiments.

FIG. 1 is a diagram of an apparatus, according to certain embodiments,for coating a first porous substrate with a thermoplastic material.

FIG. 2 is a diagram of some of the components of the apparatus accordingto other embodiments.

FIG. 3 is a cross-sectional view of a first and second porous substrateand an application head according to an embodiment.

FIG. 4 is a plan view of FIG. 3 taken along line 4.

DETAILED DESCRIPTION

As used herein, the words “comprise,” “have,” “include,” and allgrammatical variations thereof are each intended to have an open,non-limiting meaning that does not exclude additional elements or steps.

It should be understood that, as used herein, “first,” “second,”“third,” etc., are arbitrarily assigned and are merely intended todifferentiate between two or more porous substrates, holding devices,etc., as the case may be, and does not indicate any particularorientation or sequence. Furthermore, it is to be understood that themere use of the term “first” does not require that there be any“second,” and the mere use of the term “second” does not require thatthere be any “third,” etc.

As used herein, a “fluid” is a substance having a continuous phase thattends to flow and to conform to the outline of its container when thesubstance is tested at a temperature of 71° F. (22° C.) and a pressureof one atmosphere “atm” (0.1 megapascals “MPa”). A fluid can be a liquidor gas.

Oil and gas hydrocarbons are naturally occurring in some subterraneanformations. A subterranean formation containing oil or gas is sometimesreferred to as a reservoir. A reservoir may be located under land or offshore. Reservoirs are typically located in the range of a few hundredfeet (shallow reservoirs) to a few tens of thousands of feet (ultra-deepreservoirs). In order to produce oil or gas, a wellbore is drilled intoa reservoir or adjacent to a reservoir.

A well can include, without limitation, an oil, gas, water, or injectionwell. A well used to produce oil or gas is generally referred to as aproduction well. As used herein, a “well” includes at least onewellbore. A wellbore can include vertical, angled, and horizontalportions, and it can be straight, curved, or branched. As used herein,the term “wellbore” includes any cased, and any uncased, open-holeportion of the wellbore. A near-wellbore region is the subterraneanmaterial and rock of the subterranean formation surrounding thewellbore. As used herein, a “well” also includes the near-wellboreregion. The near-wellbore region is generally considered to be theregion within about 100 feet of the wellbore. As used herein, “into awell” means and includes into any portion of the well, including intothe wellbore or into the near-wellbore region via the wellbore.

A portion of a wellbore may be an open hole or cased hole. In anopen-hole wellbore portion, a tubing string can be placed into thewellbore. The tubing string allows fluids to be introduced into orflowed from a remote portion of the wellbore. In a cased-hole wellboreportion, a casing is placed into the wellbore which can also contain atubing string. A wellbore can contain an annulus. Examples of an annulusinclude, but are not limited to: the space between the wall of thewellbore and the outside of a tubing string in an open-hole wellbore;the space between the wall of the wellbore and the outside of a casingin a cased-hole wellbore; and the space between the inside of a casingand the outside of a tubing string in a cased-hole wellbore.

In unconsolidated or loosely consolidated subterranean formations (knownas soft formations), fines, such as sediment and sand, can enter thetubing string during the production of oil or gas. When this occurs,several problems can arise, for example, erosion of productionequipment, well plugging, decreased production of oil or gas, orproduction of the fines along with the oil or gas.

Sand control is often used in soft formations. Examples of sand controltechniques include, but are not limited to, depositing a filtercake in aportion of the soft formation, using slotted liners and/or screens, andgravel packing.

In filtercake deposition, a fluid (such as a slurry), that commonlyincludes calcium carbonate and polymers, is introduced into thewellbore. The fluid flows into a desired portion of the subterraneanformation. The ingredients in the fluid can form a permeable network,known as the filtercake, which binds fines, such as sand, together.After the filtercake has formed, oil or gas can be produced through theinterconnected pores in the filtercake, but most of the fines willremain bound to the filtercake and not be produced along with the oil orgas.

It is often desirable to remove at least a portion of a filtercake atsome stage in the production process. One common technique for removinga filtercake is to perform an acid wash. In an acid wash, a wash pipe isinserted into the wellbore. An acid is then flowed through the wash pipeand into the desired portion of the formation. The acid can come incontact with the filtercake. The acid can Chemically react with some ofthe ingredients in the filtercake, causing those ingredients tosolubilize, and thus causing the filtercake to be removed from thesubterranean formation.

Another sand control technique is using slotted liners and/or screens. Aslotted liner can be a perforated pipe, such as a blank pipe. A screenusually contains holes that are smaller than the perforations in aslotted liner. The liner and/or screen can cause bridging of the finesagainst the liner or screen as oil or gas is being produced. Gravelpacking is often performed in conjunction with the use of slotted linersand screens. Gravel is proppant having a particle-size class above sand,which is defined as having a largest dimension ranging from greater than2 millimeters (mm) up to 64 mm. Gravel is commonly placed in a portionof an annulus between the wall of the wellbore and the outside of thescreen. The gravel helps to trap fines from entering the productionequipment or plugging the porous portions of the liner or screen.

Some of the problems associated with using a screen include, prematureplugging of the holes in the screen and corrosion of the screen viacontact with corrosive fluids in the well. In order to help protect ascreen, the screen can be coated with a variety of materials. Athermoplastic material can be used to coat a porous substrate, such as aperforated pipe or a screen. As used herein, the term “thermoplastic”means a material that becomes liquid when heated, freezes to a solid,glassy substance when cooled sufficiently, and is capable of beingremelted and remoulded. A thermoplastic material includes bothcrystalline regions and amorphous regions. The crystalline regionscontribute to the material's strength and rigidity properties, while theamorphous regions contribute elastic properties. A thermoplasticmaterial is elastic and flexible above the glass transition temperaturethat is specific for each type of material. The glass transitiontemperature is normally the midpoint in a temperature range for thatmaterial, which is in contrast to the melting point of a purecrystalline substance, such as water.

Because it is common for a section of a perforated pipe and a screen tobe at least 30 feet long, it is difficult to coat the entire section ofpipe or screen using a thermoplastic material. It is impossible, ordifficult at best, to use prior coating methods to coat an entiresection of pipe or screen in one application when the coating is athermoplastic material. A novel method of coating a porous substratewith a thermoplastic material comprises application of the material fromthe outside of the porous substrate (i.e., from the outer diameter orouter perimeter of the porous substrate).

A method of coating a first porous substrate with a thermoplasticmaterial comprises the steps of: rotating the substrate about an axis ofthe substrate; and applying the material in a liquefied state onto thesubstrate, wherein the step of applying is performed from the outside ofthe substrate. In another embodiment, a method of coating a poroussubstrate with a thermoplastic material comprises the steps of:connecting a first porous substrate to a rotator; rotating the substrateabout an axis of the substrate; pumping the material in a liquefiedstate from a receptacle to an application head; and applying thematerial in a liquefied state onto the substrate, wherein the step ofapplying is performed from the outside of the substrate. Some of theadvantages of the coated substrate include: the material coated on thesubstrate can help prevent premature plugging of the substrate due tofines migration; the material coated on the substrate can provide achemical means by which to help dissolve at least a portion of afiltercake; and the coated substrate can provide a non-porous media. Asused herein, the term “substrate” means an object having at least onesurface to which a substance (e.g., a thermoplastic material) adheres.As used herein, the term “porous” means openings, such as holes orperforations, in a substrate that allow fluid to flow through.

Turning to the Figures, FIG. 1 is a schematic of the apparatus 10according to an embodiment for coating a porous substrate. FIG. 2 is aschematic of the apparatus 10 according to certain embodiments forcoating the porous substrate. The method includes coating at least afirst porous substrate with a thermoplastic material. The material iscapable of being heated to a liquid state. The material is capable ofbeing cooled to a solid state. The material is capable of being reheatedfrom a solid state into a liquid state. According to an embodiment, thematerial is capable of removing at least a portion of a filtercake. Forexample, the material can remove the filtercake by dissolving some ofthe ingredients of the filtercake. Accordingly, the material can removeat least a portion of a filtercake by chemically reacting with at leastsome of the ingredients in the filtercake, thus causing thoseingredients to solubilize. Preferably, the material is an acid. By wayof example, if the material is an acid and is contacted with water, thensome of the compounds in the material can dissociate and free uphydrogen ions. These hydrogen ions can then chemically react with atleast some of the ingredients (e.g., calcium carbonate) in thefiltercake, thus causing those ingredients to solubilize. According toan embodiment, the material is selected from the group consisting ofpolylactic acid, polyglycolic acid, and combinations thereof.

The method includes coating at least a first porous substrate. Themethod can further include coating a second porous substrate. The poroussubstrate can be any type of substrate that is capable of being coatedwith a thermoplastic material. It is to be understood that any referenceto “the substrate” is meant to include a first substrate (singular), asecond substrate (singular), or a first and second or more substrates(plural) without the need to continually refer to the substrate in both,the singular and plural forms.

The substrate 401/402 is preferably hollow. In one embodiment, thesubstrate is tubular in shape. If the substrate is tubular in shape,then the substrate will have an outer diameter (O.D.) and an innerdiameter (I.D.). According to another embodiment, the substrate isnon-tubular in shape. Examples of non-tubular shapes include, but arenot limited to, a square, a rectangle, and a triangle. If the substrateis non-tubular in shape, then the substrate will have an outer perimeterand an inner perimeter. An example of a first substrate 401 includes,but is not limited to, a screen. As depicted in FIG. 3, the first poroussubstrate 401 is a wire-wrap screen. An example of a second substrate402 includes, but is not limited to, a pipe. The pipe can be perforated(causing the pipe to be porous) and the screen can contain holes(causing the screen to be porous). According to another embodiment, andas depicted in FIGS. 3 and 4, the second substrate 402 is positionedinside the first substrate 401. For example, the pipe can be positionedinside the screen. According to another embodiment, the second poroussubstrate can be attached to the first porous substrate. For example,and as depicted in FIG. 3, the second porous substrate 402 (e.g., apipe) can be attached at its O.D. to the I.D. of the first poroussubstrate 401 (e.g., a screen). There can also be a space between thesecond porous substrate 402 and the first porous substrate 401, asdepicted in FIG. 4.

The method can further include the step of connecting the substrate401/402 to a rotator 501. The rotator 501 can be connected to a firstholding device 500. The apparatus 10 can further include a secondholding device 500. Preferably, the substrate 401/402 is connected atone end to the rotator 501, which is connected to the first holdingdevice 500 and connected at the other end to the second holding device500. According to another embodiment, the second holding device 500further includes a rotator 501. In an embodiment, the rotator(s) 501 iscapable of rotating the substrate. Preferably, the substrate 401/402 iscapable of free rotation about its axis. For example, the substrate401/402 can be connected to the rotator(s) 501 and/or the second holdingdevice 500 such that neither the rotator nor the holding device impedesrotation of the substrate.

The method includes the step of rotating the substrate 401/402 about anaxis of the substrate 401/402. The substrate can be rotated at a desiredfrequency. For example, the rotator 501 can be set to rotate at thedesired frequency, such as a desired revolutions per minute (rpm's). Thedesired frequency can be selected based on a desired weight of thematerial to be coated on a given length of the substrate. For example,the desired frequency can be selected based on how many pounds of thematerial is to be coated on each foot of the substrate 401/402 (1 b/ft).The desired weight per length can vary.

The material can be held or stored in a receptacle 100. At roomtemperatures, the material is preferably in a solid state 101. Thereceptacle 100 can further comprise a receptacle heating element 103.The method can further include the step of heating at least a portion ofthe material in the receptacle 100 to a liquefied state 102. Thereceptacle heating element 103 is depicted in FIG. 1 as being positionedtowards the top of the receptacle 100 and on top of the material;however, the element 103 can also be positioned at a location other thantowards the top of the receptacle. For example, the element 103 can alsobe positioned at the bottom or towards the bottom of the receptacle 100.According to an embodiment, at least a portion of the material containedin the receptacle 100 is heated via the receptacle heating element 103.Preferably, the at least a portion of the material is heated to at leasta temperature such that the material becomes a liquid 102.

The method can also include the step of pumping the thermoplasticmaterial in a liquefied state 102 from the receptacle 100 to anapplication head 302. The step of pumping can occur after the step ofheating at least a portion of the material in the receptacle 100 to aliquefied state 102. The apparatus 10 can comprise a pump 104. The pump104 can be located adjacent to the receptacle heating element 103.Preferably, the pump 104 comprises a pump heating element (not shown).If the receptacle heating element 103 is located at a position otherthan at the top of the material (such as at the bottom of the receptacle100), then the apparatus 100 can further include a pump tubing (notshown). The pump tubing can be positioned inside the receptacle.Accordingly, one end of the pump tubing can contact the liquefiedmaterial 102 contained in the receptacle 100 and the other end of thepump tubing can be connected to the pump 104. The method can furtherinclude the step of activating the pump 104 to pump the material in aliquefied state 102 from the receptacle 100 to the application head 302.According to an embodiment, when the pump is activated, the liquefiedmaterial 102 will travel through the pump tubing towards the pump.

The apparatus 10 can further include a feed tube 200. The feed tube 200can be connected at one end to the pump 104 and connected at the otherend to the application head 302. In this manner, the pump 104 can causethe liquefied material to move from the receptacle 100, through the feedtube 200, and into the application head 302. According to an embodiment,the pump has a variable flow rate. For example, the pump 104 can be usedto control the flow rate of the material in a liquefied state 102 fromthe receptacle 100 to the application head 302. Preferably, the feedtube 200 is heated. By heating the feed tube 200, the material can bemaintained in a liquefied state. The feed tube 200 is preferably heatedto at least a minimum temperature such that the material is maintainedin a liquefied state 102.

According to certain embodiments, the material is pumped into theapplication head 302. Preferably, the application head 302 furthercomprises an application head heating element (not shown). In thismanner, the material can be maintained in a liquefied state. Thetemperature of the application head heating element is preferablyvariable. The temperature of the application head heating element can beset to a desired temperature. In a preferred embodiment, the desiredtemperature is at least a minimum temperature such that the material ismaintained in a liquefied state.

According to an embodiment, the application head 302 is positionedrelative to the outside of at least a portion of the substrate 401/402.In a preferred embodiment, the application head 302 completely surroundsthe outside of at least a portion of the substrate 401/402 (shown inFIGS. 1 and 3). The application head 302 can further comprise a seal 305(shown in FIGS. 3 and 4). The seal 305 can contact the O.D. of the firstsubstrate 401. In this manner, the seal 305 can help apply the materialonto the substrate 401/402.

The method includes the step of applying the material in a liquefiedstate onto the substrate, wherein the step of applying is performed fromthe outside of the substrate. Examples of applying include, but are notlimited to, spraying the material onto the substrate, flowing thematerial onto the substrate, and injecting the material into thesubstrate. It should be understood that the step of applying can beperformed in a variety of ways such that the material is maintained in aliquefied state 102 and can be applied from the outside of the substrateonto and/or into the substrate, and the preceding examples are not to beconstrued as the only ways of achieving such a result. When there isonly a first porous substrate 401, the step of applying can compriseapplying the liquefied material onto the O.D. of the first substratethrough the porous portion of the first substrate and into the I.D. ofthe first substrate. When there is a first and second porous substrate401 and 402, the step of applying can comprise applying the liquefiedmaterial onto the O.D. of the first substrate 401, through the porousportion of the first substrate, through the I.D. of the first substrate,and then onto the O.D. of the second substrate 402, through the porousportion of the second substrate, and into the I.D. of the secondsubstrate. The step of applying can comprise injecting the material ontothe O.D. and into the porous portions and the I.D. The step of applyingcan comprise forcing the material onto the O.D. and into the porousportions and the I.D. Preferably, the material is capable of adhering toa surface of the substrate 401/402. According to an embodiment, thematerial coats the O.D. and the I.D. of the substrate 401/402. Accordingto this embodiment, it is preferred that the material fills the porousportions of the substrate. The material in a liquefied state, can coatthe outside of the substrate, fill the porous portions of the substrate,and coat the inside of the substrate.

The method can further include the step of causing the application head302 to travel axially along the length of the substrate 401/402. Theapparatus 10 can also include a drive motor 301. The drive motor 301 canbe connected in any manner that allows for movement of the applicationhead 302. By way of example, the drive motor 301 can be connecteddirectly to the application head 302. By way of another example, and asdepicted in FIG. 2, the drive motor 301 can be connected to anapplication head platform 303. In this embodiment, the application head302 can also be connected to the platform 303. The apparatus 10 can alsoinclude a first pair of guide rails 502 and optionally, a second pair ofguide rails 503. The rails can help guide and support the applicationhead 302 or the application head and the drive motor 302 and 301.Preferably, the platform 303 travels axially along the length of thesubstrate unimpeded. The platform 303 can further include a mobilizer, apair, or more than one pair of mobilizers 304. The mobilizer 304 can beany device that allows or assists the platform 303, and the applicationhead 302, or the application head and drive motor 302 and 301, to travelalong the guide rails 502/503. An example of a mobilizer includes, butis not limited to, a wheel 304. According to certain embodiments, thedrive motor 301 and the application head 302 travel axially along thelength of the substrate. According to other embodiments, the drive motor301, the application head 302, and the platform 303 travel axially alongthe length of the substrate.

The distance that the application head 302 (and any other components)travels axially along the substrate 401/402 can be controlled. Accordingto an embodiment, the application head 302 (and any other components)travels axially along the length of the substrate 401/402 for a desireddistance. Preferably, the length of the feed tube 200 is such that itallows the application head 302 (and any other components) to travelaxially along the length of the substrate 401/402 for the desireddistance. In one embodiment, the desired distance is at least 90% of thetotal length of the substrate 401/402. According to another embodiment,the desired distance is the entire length of the substrate 401/402.

The step of applying can further include coating the substrate 401/402with a desired quantity of the material per a given length of thesubstrate. For example, the substrate can be coated with a desiredpounds of material per foot of substrate (lbs/ft). One of the advantagesof the material is that it can be used to help remove a portion offiltercake. When the material is to be used for removing a portion of afiltercake, then the desired quantity of coated material can bedetermined based on the concentration of certain ingredients in thefiltercake (e.g., the concentration of calcium carbonate). By way ofexample, the desired quantity can be determined based on the amount ofavailable acid from the material capable of dissolving at least aportion of a filtercake containing a given concentration of calciumcarbonate. In order to achieve the desired quantity of coating, it maybe necessary to apply excess material in a liquefied state 102 onto thesubstrate 401/402 because some of the material being applied onto thesubstrate may not adhere to the substrate. The desired quantity can beachieved by at least regulating the flow rate of the fluid out of theapplication head or regulating the speed at which the application headtravels along the length of the substrate. The substrate 401/402 can becoated a second time to achieve the desired quantity. There may be otherways of achieving the desired quantity, and the preceding examples arenot meant to be construed as the only ways of achieving such a result.

The method includes the step of rotating the substrate 401/402 about anaxis of the substrate 401/402. The substrate 401/402 can be rotated fora desired period of time. According to an embodiment, the desired periodof time is at least how long it takes for the application head 302 totravel the desired distance along the length of the substrate 401/402.According to another embodiment, the desired period of time is at least10 minutes after the application head 302 has traveled the desireddistance along the length of the substrate 401/402. According to yetanother embodiment, the desired period of time is the time it takes forthe material to become a solid on the substrate after the step ofapplying. According to certain embodiments, because the substrate401/402 is being rotated at least for the time that the material isbeing applied onto the substrate 401/402, the material in a liquefiedstate is inhibited from collecting or pooling on at least a portion ofthe I.D. of the substrate 401/402. Referring to FIG. 3, without therotation of the substrate 401/402, the material in a liquefied state102, can collect or pool at the bottom of the substrate 401/402.Moreover, by rotating the substrate 401/402 during the step of applying,the material can flow from the I.D. of the substrate back through theporous portions of the substrate and onto the O.D. of the substrate,providing a better coating on the substrate. The method can furthercomprise the step of cooling the material or allowing the material tocool to a solid state after the step of applying.

The apparatus 10 can further include a collector 600. The collector 600can collect any excess material that does not adhere to the substrate401/402.

The coated substrate can be used for a variety of applications. Oneexample of such an application is the oil and gas industry. In anembodiment, the method can further include the step of placing thecoated substrate 401/402 in at least a portion of a subterraneanformation after the step of applying. If the method includes the step ofcooling or allowing to cool, then the step of placing can occur afterthe step of cooling or allowing to cool. According to this embodiment,the method can also include the step of contacting the substrate 401/402with a liquid, such as water, to cause at least a portion of thematerial to remove at least a portion of a filtercake.

In some applications, it would be desirable to remove the material orallow the material to be removed from the substrate 401/402 after acertain length of time. For example, in the case where the coatedsubstrates include a perforated pipe and a screen, and the substratesare used in a wellbore, it may be desirable to remove the material orallow the material to be removed from the substrates after a desiredperiod of time (such as for production of oil or gas from thesubterranean formation). Preferably, the material is capable of beingremoved from the substrate at a predetermined length of time. Examplesof removing or allowing the material to be removed include, but are notlimited to: allowing the coated material to come in contact with atleast a minimum temperature high enough to heat the material to aliquefied state; contacting the material with a heat source (e.g., aheated liquid or a heated gas) such that the material becomes a liquid;allowing the material to come in contact with a compound that at leastpartially solubilizes the material; and contacting the material with acompound that at least partially solubilizes the material.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is, therefore, evident thatthe particular illustrative embodiments disclosed above may be alteredor modified and all such variations are considered within the scope andspirit of the present invention. While compositions and methods aredescribed in terms of “comprising,” “containing,” or “including” variouscomponents or steps, the compositions and methods also can “consistessentially of” or “consist of” the various components and steps.Whenever a numerical range with a lower limit and an upper limit isdisclosed, any number and any included range falling within the range isspecifically disclosed. In particular, every range of values (of theform, “from about a to about b,” or, equivalently, “from approximately ato b”) disclosed herein is to be understood to set forth every numberand range encompassed within the broader range of values. Also, theterms in the claims have their plain, ordinary meaning unless otherwiseexplicitly and clearly defined by the patentee. Moreover, the indefinitearticles “a” or “an”, as used in the claims, are defined herein to meanone or more than one of the element that it introduces. If there is anyconflict in the usages of a word or term in this specification and oneor more patent(s) or other documents that may be incorporated herein byreference, the definitions that are consistent with this specificationshould be adopted.

What is claimed is:
 1. A method of coating a first porous substrate witha thermoplastic material comprising the steps of: rotating the substrateabout an axis of the substrate, wherein the substrate is a pipe or ascreen, and wherein the substrate is part of a sand control assembly;and applying the material in a liquefied state onto the substrate,wherein the step of applying is performed from the outside of thesubstrate, and wherein the step of applying comprises applying theliquefied material from the outer diameter of the substrate through theporous portion of the substrate and into the inner diameter of thesubstrate.
 2. The method according to claim 1, wherein the material isselected from the group consisting of polylactic acid, polyglycolicacid, and combinations thereof.
 3. The method according to claim 1,further comprising coating a second porous substrate.
 4. The methodaccording to claim 3, wherein the first substrate and the secondsubstrate are hollow.
 5. The method according to claim 1, furthercomprising the step of connecting the substrate to a rotator.
 6. Themethod according to claim 1, wherein the substrate is rotated at adesired frequency.
 7. The method according to claim 1, furthercomprising an application head.
 8. The method according to claim 7,wherein the application head further comprises an application headheating element.
 9. The method according to claim 7, wherein theapplication head is positioned relative to the outside of at least aportion of the substrate.
 10. The method according to claim 9, whereinthe application head completely surrounds the outside of at least aportion of the substrate.
 11. The method according to claim 7, furthercomprising the step of pumping the material in a liquefied state from areceptacle to the application head.
 12. The method according to claim11, wherein the receptacle further comprises a receptacle heatingelement.
 13. The method according to claim 7, further comprising thestep of causing the application head to travel axially along the lengthof the substrate during the step of applying.
 14. The method accordingto claim 13, wherein the application head travels axially along thelength of the substrate for a desired distance.
 15. The method accordingto claim 1, wherein the substrate is rotated for a desired period oftime.
 16. The method according to claim 15, wherein the desired periodof time is the time it takes for the material to become a solid on thesubstrate.
 17. A method of coating a first porous substrate with athermoplastic material comprising the steps of: rotating the substrateabout an axis of the substrate, wherein the substrate is a pipe orscreen, and wherein the substrate is part of a sand control assembly;and applying the material in a liquefied state onto the substrate,wherein the step of applying is performed from the outside of thesubstrate, wherein the material coats the outside of the substrate,fills the porous portion of the substrate, and coats the inside of thesubstrate during the step of applying.
 18. The method according to claim17, wherein the step of applying further comprises coating the substratewith a desired quantity of the material per a given length of thesubstrate.
 19. A method of coating a porous substrate with athermoplastic material comprising the steps of: connecting a firstporous substrate to a rotator, wherein the substrate is a pipe or ascreen, and wherein the substrate is part of a sand control assembly;rotating the substrate about an axis of the substrate; pumping thematerial in a liquefied state from a receptacle to an application head;and applying the material in a liquefied state onto the substrate,wherein the step of applying is performed from the outside of thesubstrate, and wherein the inside of the substrate is fully or partiallycoated with the material during the step of applying.
 20. The methodaccording to claim 19, wherein the substrate has an outer diameter andan inner diameter.